"Not really. Differences between Android and iOS aside, Galaxy Ace is cheap low budget phone. You would need to be looking at Samsung Galaxy S for comparison to iPhone 4."

And the Samsung Wave II with the Bada OS but no AMOLED screen. I got mine for £100 at the CPW clearance. It has a similar set-up under the hood to the Galaxy S. According to GSMArena "1 GHz ARM Cortex-A8 processor, PowerVR SGX540 GPU, Hummingbird chipset"